<mat-card class="example-card">
    <mat-card-header>
        Enter call information
    </mat-card-header>
    <mat-card-content>
        <form (ngSubmit)="onCallSubmit()" class="form-control">

            <mat-form-field id="romm" class="form-control">
                <mat-label>Room</mat-label>
                <input matInput placeholder="" 
                    [(ngModel)]="room" name="room"
                >
            </mat-form-field>
            <br> <br>
            <mat-form-field appearance="fill">
                <mat-label>Select Server</mat-label>
                <mat-select [(value)]="serverOption">
                    <mat-option value="sangatel">Sangatel</mat-option>
                    <mat-option value="jaac">jaac</mat-option>
                </mat-select>
              </mat-form-field>

              <!-- <mat-form-field appearance="fill">
                <mat-label>Select</mat-label>
                <mat-select>
                  <mat-option value="one">First option</mat-option>
                  <mat-option value="two">Second option</mat-option>
                </mat-select>
              </mat-form-field> -->

            <br><br>

            <br> <br>
            <button mat-button color="primary" type="submit" class="btn btn-success">Call_1</button>
            <br> <br>
        </form>

        <button mat-button color="warning" (click)="ping()"  class="btn btn-success">ping</button>

    </mat-card-content>
</mat-card>